Synaptic vesicle glycoprotein 2C enhances vesicular storage of dopamine and counters dopaminergic toxicity

• Type of Material: Article
• Authors: Meghan L Bucher, Columbia University; Amy R Dunn, Emory University; Joshua M Bradner, Emory University; Kristen Stout Egerton, Emory University; James P Burkett, Emory University; Michelle A Johnson, Emory University; Gary W Miller, Columbia University
• Language: English
• Date: 2023-06-26
• Publisher: NIH
• Publication Version: Preprint (Prior to Peer Review)
• Copyright Statement: The copyright holder for this preprint is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY-NC 4.0 International license.
• License: Creative Commons Attribution-NoDerivs 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1101/2023.06.26.546143
• Title of Journal or Parent Work: bioRxiv
• Grant/Funding Information: This work was funded by National Institutes of Health R01ES023839 (GWM), U18DA052498 (GWM), F31NS089242 (ARD), F31DA037652 (KSE), T32ES007322 (MLB), and Parkinson’s Foundation PF-PRF-933478 (MLB),
• Keywords: axonal arborizations; Parkinson’s disease; Dopaminergic neurons; dopamine
• Research Categories: Environmental Sciences; Health Sciences, Mental Health; Biology, Cell; Health Sciences, Epidemiology; Health Sciences, Public Health

Abstract

Dopaminergic neurons of the substantia nigra exist in a persistent state of vulnerability resulting from high baseline oxidative stress, high energy demand, and broad unmyelinated axonal arborizations. Impairments in the storage of dopamine compound this stress due to cytosolic reactions that transform the vital neurotransmitter into an endogenous neurotoxicant, and this toxicity is thought to contribute to the dopamine neuron degeneration that occurs Parkinson’s disease. We have previously identified synaptic vesicle glycoprotein 2C (SV2C) as a modifier of vesicular dopamine function, demonstrating that genetic ablation of SV2C in mice results in decreased dopamine content and evoked dopamine release in the striatum. Here, we adapted a previously published in vitro assay utilizing false fluorescent neurotransmitter 206 (FFN206) to visualize how SV2C regulates vesicular dopamine dynamics and determined that SV2C promotes the uptake and retention of FFN206 within vesicles. In addition, we present data indicating that SV2C enhances the retention of dopamine in the vesicular compartment with radiolabeled dopamine in vesicles isolated from immortalized cells and from mouse brain. Further, we demonstrate that SV2C enhances the ability of vesicles to store the neurotoxicant 1-methyl-4-phenylpyridinium (MPP+) and that genetic ablation of SV2C results in enhanced 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced vulnerability in mice. Together, these findings suggest that SV2C functions to enhance vesicular storage of dopamine and neurotoxicants, and helps maintain the integrity of dopaminergic neurons.